The inventive concepts herein relate to semiconductor devices, and more particularly, to a clock gating circuit that operates at high speed.
In general, digital systems may be classified as combination circuits and sequential circuits. A combination circuit is constituted by logic gates, and outputs of the logic gates are sequentially determined by current input values. A combination circuit performs an information processing operation that may be logically expressed by a series of Boolean expressions. Sequential circuits use a storage device such as a flip-flop which may be constituted by additional logic gates. An output of the storage device is a function of a current input and a state of the storage device. The state of the storage device is a function of previous inputs.
A digital system includes a plurality of functional blocks to perform an information processing operation. However, not every functional block is used while performing a particular information processing operation. Thus, it is necessary to block provision of a clock signal to a block that does not operate during a particular processing operation, so as to reduce power consumption or heating. A clock gating circuit performs the function of blocking provision of a clock signal to a functional block that does not operate in a digital system.